Add Targeted LiveDebugValues Tests That Exercise Specific Expected Behaviours

[TWeaver]

Summary

Within in this patch are 22 distinct test cases that exercise specific behaviours within the livedebug values pass.

After all the work that's been ongoing with the livedebugvalues pass its become clear that coverage for the expected behaviour was previously lacking.

Rather than risk there not being coverage for said cases I felt it was time to get them added to reduce the risk of a regression in the future.

The aim is to cover behaviour for a standard case with no moves or clobbers, cases with clobbers and cases with moves.

A mix of sequential, loop and diamond control flows are considered in the flavours described above.

happy reviewing.

[vsk]

This is great, thanks for doing this.

[vsk]

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond_one_move.mir

18

Have you considered running FileCheck with -implicit-check-not=DBG_VALUE? That might be less brittle (e.g. it'd survive small changes to how DBG_VALUE is printed out).

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_loop.mir

6

nit, it's -> its

llvm/test/DebugInfo/MIR/X86/livedebugvalues_bb_to_bb.mir

5

nit, propogate -> propagate

6

This one isn't a loop, it seems. Just a chain of jumps?

llvm/test/DebugInfo/MIR/X86/livedebugvalues_bb_to_bb_clobbered.mir

11

Is the interesting thing here the undef DBG_VALUE? Could this be:

; CHECK-LABEL: bb.1.bb1:
; CHECK:       DBG_VALUE $ebx, $noreg, !16
; CHECK:       $ebx = MOV32ri 0
; CHECK:       DBG_VALUE $noreg, $noreg, !16

?

If so it might be another argument to have an implicit check-not for DBG_VALUE in these tests.

[djtodoro]

Thanks for this!

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond.mir

31

(Nit) Please update the version of the compiler.

[TWeaver]

thank you all for your valuable time.

added implicit-check-not=DBG_VALUE to all tests.
added extra coverage missing from one of the tests.
removed some trailing whitespace.
fixed few typo nits.

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond.mir

31

Hi Dj,

thanks for your review.

All of the tests have clang 8.0 as their versions as they're all based on some samples written about a year ago now.

Are you wanting me to change the strings in the debug info to the latest version of clang or regenerate these samples?

the samples are hand modified from one base sample that was trimmed down from a larger test case.

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond_one_move.mir

18

Hi VSK,

I wasn't fully aware of the -implicit-check feature of FileCheck until you mentioned it.

I've added it to all tests and it actually flushed out a lack of coverage in one of the tests.

thank you very much for pointing this out. Some of the test cases have been significantly reduced as a result.

[TWeaver]

address feedback

[aprantl]

Very nice!

[aprantl]

Very nice!

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond.mir

5

Wording: "debug value intrinsics" are call llvm.dbg.value in LLVM IR. In MIR they are DBG_VALUE *instructions*.

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_within_loop_outer_moved.mir

5

propagated

[vsk]

LGTM as well.

[TWeaver]

addressed further feedback

[TWeaver]

updated diff

[TWeaver]

I'll land this tomorrow as I'm off home now and don't want to risk getting buildbot emails all night.

thanks for the reviews!

[djtodoro]

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond.mir

31

Hi Tom,

Yes I just wanted the "clang version 10" as a string field there, since we are testing the LLVM 10 and somewhere outhere might be a testing tool parsing the metadata...
I mean, it is a very minor thing, other than that, everything looks fine! Thanks!

[thakis]

This breaks check-llvm on most bots, see e.g. http://lab.llvm.org:8011/builders/clang-atom-d525-fedora-rel/builds/31667/steps/ninja%20check%201/logs/FAIL%3A%20LLVM%3A%3Alivedebugvalues_loop_within_loop_clobbered.mir

Please take a look and revert while you investigate if the fix isn't obvious.

[vsk]

@TWeaver this is still causing a failure on some Darwin bots:

error: /Volumes/JenkinsData/workspace/apple-clang-stage1-configure-R_master/llvm-project/llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_within_loop_clobbered.mir:40:39: expected end of metadata node
  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)

Could you please take a look?

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propogated through a CFG containing
+  ; a diamond that doesn't move or clobber their locations.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1, %bb.2
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.1.bb1:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    JMP_1 %bb.3
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond_match_clobber.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are only propogated into the top blocks of
+  ; a diamond when the location is clobbered and not into the successor block.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-NEXT:  $ebx = MOV32ri 0, debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-NEXT:  $ebx = MOV32ri 0, debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1, %bb.2
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.1.bb1:
+    successors: %bb.3
+    $ebx = MOV32ri 0, debug-location !17
+    JMP_1 %bb.3
+  bb.2.bb2:
+    successors: %bb.3
+    $ebx = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond_match_move.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propogated correctly through a
+  ; diamond CFG when the location is moved by another instruction.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-NEXT:  $eax = MOV32ri 0, debug-location !17
+  ; CHECK-NEXT:  DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-NEXT:  $eax = MOV32ri 0, debug-location !17
+  ; CHECK-NEXT:  DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1, %bb.2
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.1.bb1:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+    JMP_1 %bb.3
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond_one_clobber.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into a successor block
+  ; of a diamond CFG that clobbers its location.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1, %bb.2
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.1.bb1:
+    successors: %bb.3
+    $ebx = MOV32ri 0, debug-location !17
+    JMP_1 %bb.3
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_diamond_one_move.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into a successor block
+  ; of a diamond CFG that moves its location.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-NEXT:  $eax = MOV32ri 0, debug-location !17
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1, %bb.2
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.1.bb1:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+    JMP_1 %bb.3
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_basic_loop.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propagated throughout a CFG with a
+  ; loop that doesn't move or clobber its location.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.1, %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_bb_to_bb.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propagated throughout a basic
+  ; sequential CFG.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name:            _Z8bb_to_bb
+body:             |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_bb_to_bb_clobbered.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propagated into basic blocks with no
+  ; control flow when it's location is clobbered.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name:            _Z8bb_to_bb
+body:             |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $ebx = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_bb_to_bb_move_to_clobber.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are correctly propagated into blocks with
+  ; no control flow when a location is moved and then clobbered.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-NEXT:  $eax = MOV32ri 0, debug-location !17
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name:            _Z8bb_to_bb
+body:             |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+    DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+    $ebx = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_break.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are correctly propagated into a loop with
+  ; break.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.4.bb4:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb4, !dbg !17
+  bb4:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.3, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.4, 4, implicit killed $eflags
+  bb.3.bb3:
+    successors: %bb.1, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.4.bb4:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_break_clobbered.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are correctly propagated when dealing
+  ; with a loop that clobbers its location and has two exit points (a break).
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb4, !dbg !17
+  bb4:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.3, %bb.4
+    $ebx = MOV32ri 0, debug-location !17
+    JCC_1 %bb.4, 4, implicit killed $eflags
+  bb.3.bb3:
+    successors: %bb.1, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.4.bb4:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_clobbered.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into a loop that
+  ; clobbers it's location.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\test")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+
+  bb.2.bb2:
+    successors: %bb.1, %bb.3
+    $ebx = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_diamond.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propagated into a loop with
+  ; diamond pattern and beyond.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.4.bb4:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.5.bb5:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb3, !dbg !17
+  bb4:
+    br label %bb3, !dbg !17
+  bb5:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2, %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.3, 4, implicit killed $eflags
+  bb.2.bb2:
+    successors: %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JMP_1 %bb.4
+  bb.3.bb3:
+    successors: %bb.4
+    $eax = MOV32ri 0, debug-location !17
+  bb.4.bb4:
+    successors: %bb.1, %bb.5
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.5.bb5:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_diamond_clobber.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into a loop with
+  ; diamond pattern that clobbers it's location.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb3, !dbg !17
+  bb4:
+    br label %bb3, !dbg !17
+  bb5:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2, %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.3, 4, implicit killed $eflags
+  bb.2.bb2:
+    successors: %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JMP_1 %bb.4
+  bb.3.bb3:
+    successors: %bb.4
+    $ebx = MOV32ri 0, debug-location !17
+  bb.4.bb4:
+    successors: %bb.1, %bb.5
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.5.bb5:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_diamond_move.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propagated into a loop with
+  ; diamond pattern but not beyond.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.4.bb4:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.5.bb5:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb3, !dbg !17
+  bb4:
+    br label %bb3, !dbg !17
+  bb5:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2, %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.3, 4, implicit killed $eflags
+  bb.2.bb2:
+    successors: %bb.4
+    $ebx = MOV32ri 0, debug-location !17
+    JMP_1 %bb.4
+  bb.3.bb3:
+    successors: %bb.4
+    $ebx = MOV32ri 0, debug-location !17
+  bb.4.bb4:
+    successors: %bb.1, %bb.5
+    $ebx = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.5.bb5:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_early_clobber.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into a loop that
+  ; clobbers it's location.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $ebx = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.1, %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.3.bb3:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_two_backedge.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are prapogated into a loop that has two
+  ; backedges and beyond.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.4.bb4:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb4, !dbg !17
+  bb4:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.1, %bb.3
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.3.bb3:
+    successors: %bb.1, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.4.bb4:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_two_backedge_clobbered.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into loops that clobber
+  ; their locations and have two backedges.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb4, !dbg !17
+  bb4:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2
+    $eax = MOV32ri 0, debug-location !17
+  bb.2.bb2:
+    successors: %bb.1, %bb.3
+    $ebx = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.3.bb3:
+    successors: %bb.1, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.4.bb4:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_within_loop.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are propagated into loops within loops.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.1.bb1:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.2.bb2:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.4.bb4:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.5.bb5:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb3, !dbg !17
+  bb4:
+    br label %bb3, !dbg !17
+  bb5:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.4, 4, implicit killed $eflags
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    successors: %bb.2, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.4.bb4:
+    successors: %bb.1, %bb.5
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.5.bb5:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_within_loop_clobbered.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into loops with inner
+  ; loops that clobber their locations.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb3, !dbg !17
+  bb4:
+    br label %bb3, !dbg !17
+  bb5:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.4, 4, implicit killed $eflags
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    successors: %bb.2, %bb.4
+    $ebx = MOV32ri 0, debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.4.bb4:
+    successors: %bb.1, %bb.5
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.5.bb5:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_within_loop_moved.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propagated into loops with inner
+  ; loops that move their locations.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.3.bb3:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb3, !dbg !17
+  bb4:
+    br label %bb3, !dbg !17
+  bb5:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.4, 4, implicit killed $eflags
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    successors: %bb.2, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.4.bb4:
+    successors: %bb.1, %bb.5
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.5.bb5:
+    RETQ $eax, debug-location !17
+...

llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_within_loop_outer_moved.mir

+--- |
+  ; RUN: llc %s -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
+
+  ; Check that DBG_VALUE instructions are not propogated into loops with inner
+  ; loops that move their locations.
+
+  ; CHECK-LABEL: bb.0.entry:
+  ; CHECK:       DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.4.bb4:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+  ; CHECK-LABEL: bb.5.bb5:
+  ; CHECK:       DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+
+  define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
+  entry:
+    br label %bb1, !dbg !17
+  bb1:
+    br label %bb2, !dbg !17
+  bb2:
+    br label %bb3, !dbg !17
+  bb3:
+    br label %bb3, !dbg !17
+  bb4:
+    br label %bb3, !dbg !17
+  bb5:
+    ret i32 0, !dbg !17
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!7, !8, !9, !10}
+  !llvm.ident = !{!11}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
+  !1 = !DIFile(filename: "main.cpp", directory: "F:\")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
+  !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !7 = !{i32 2, !"Dwarf Version", i32 4}
+  !8 = !{i32 2, !"Debug Info Version", i32 3}
+  !9 = !{i32 1, !"wchar_size", i32 2}
+  !10 = !{i32 7, !"PIC Level", i32 2}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!6, !6}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
+  !17 = !DILocation(line: 10, scope: !12)
+
+...
+---
+name: _Z8bb_to_bb
+body:  |
+  bb.0.entry:
+    successors: %bb.1
+    $ebx = MOV32ri 0, debug-location !17
+    DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
+  bb.1.bb1:
+    successors: %bb.2, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.4, 4, implicit killed $eflags
+  bb.2.bb2:
+    successors: %bb.3
+    $eax = MOV32ri 0, debug-location !17
+  bb.3.bb3:
+    successors: %bb.2, %bb.4
+    $eax = MOV32ri 0, debug-location !17
+    JCC_1 %bb.2, 4, implicit killed $eflags
+  bb.4.bb4:
+    successors: %bb.1, %bb.5
+    $eax = MOV32ri 0, debug-location !17
+    DBG_VALUE $eax, $noreg, !16, !DIExpression(), debug-location !17
+    JCC_1 %bb.1, 4, implicit killed $eflags
+  bb.5.bb5:
+    RETQ $eax, debug-location !17
+...